Buggy code:
@ SuppressCodecs ( { "Lucene3x" , "MockFixedIntBlock" , "MockVariableIntBlock" , "MockSep" , "MockRandom" , "Lucene40" , "Lucene41" , "Appending" , "Lucene42" } ) public class TestBackwardsCompatibility extends LuceneTestCase { static final String [ ] oldNames = new String [ ] { "40.cfs" , "40.nocfs" , "41.cfs" , "41.nocfs" , "42.cfs" , "42.nocfs" , "45.cfs" , "45.nocfs" } ; final String [ ] unsupportedNames = new String [ ] { "19.cfs" , "19.nocfs" , "20.cfs" , "20.nocfs" , "21.cfs" , "21.nocfs" , "22.cfs" , "22.nocfs" , "23.cfs" , "23.nocfs" , "24.cfs" , "24.nocfs" , "29.cfs" , "29.nocfs" } ; static final String [ ] oldSingleSegmentNames = new String [ ] { "40.optimized.cfs" , "40.optimized.nocfs" } ; static Map < String , Directory > oldIndexDirs ; private static IndexUpgrader newIndexUpgrader ( Directory dir ) { } @ BeforeClass public static void beforeClass ( ) throws Exception { } @ AfterClass public static void afterClass ( ) throws Exception { } public void testUnsupportedOldIndexes ( ) throws Exception { } public void testFullyMergeOldIndex ( ) throws Exception { } public void testAddOldIndexes ( ) throws IOException { } public void testAddOldIndexesReader ( ) throws IOException { } public void testSearchOldIndex ( ) throws IOException { } public void testIndexOldIndexNoAdds ( ) throws IOException { } public void testIndexOldIndex ( ) throws IOException { } private void doTestHits ( ScoreDoc [ ] hits , int expectedCount , IndexReader reader ) throws IOException { } public void searchIndex ( Directory dir , String oldName ) throws IOException { } private int compare ( String name , String v ) { } public void changeIndexWithAdds ( Random random , Directory dir , String origOldName ) throws IOException { } public void changeIndexNoAdds ( Random random , Directory dir ) throws IOException { } public File createIndex ( String dirName , boolean doCFS , boolean fullyMerged ) throws IOException { } public void testExactFileNames ( ) throws IOException { } private String asString ( String [ ] l ) { } private void addDoc ( IndexWriter writer , int id ) throws IOException { } private void addNoProxDoc ( IndexWriter writer ) throws IOException { } private int countDocs ( DocsEnum docs ) throws IOException { } public void testNextIntoWrongField ( ) throws Exception { } public void testOldVersions ( ) throws Exception { } public void testNumericFields ( ) throws Exception { } private int checkAllSegmentsUpgraded ( Directory dir ) throws IOException { } private int getNumberOfSegments ( Directory dir ) throws IOException { } public void testUpgradeOldIndex ( ) throws Exception { } public void testCommandLineArgs ( ) throws Exception { for ( String name : TestBackwardsCompatibility . oldIndexDirs . keySet ( ) ) { File dir = _TestUtil . getTempDir ( name ) ; File dataFile = new File ( TestBackwardsCompatibility . class . getResource ( ( ( "index." + name ) + ".zip" ) ) . toURI ( ) ) ; _TestUtil . unzip ( dataFile , dir ) ; String path = dir . getAbsolutePath ( ) ; List < String > args = new ArrayList < String > ( ) ; if ( random ( ) . nextBoolean ( ) ) { args . add ( "-verbose" ) ; } if ( random ( ) . nextBoolean ( ) ) { args . add ( "-delete-prior-commits" ) ; } if ( random ( ) . nextBoolean ( ) ) { Class < ? extends FSDirectory > dirImpl = ( random ( ) . nextBoolean ( ) ) ? SimpleFSDirectory . class : NIOFSDirectory . class ; args . add ( "-dir-impl" ) ; args . add ( dirImpl . getName ( ) ) ; } args . add ( path ) ; IndexUpgrader upgrader = null ; try { upgrader = IndexUpgrader . parseArgs ( args . toArray ( new String [ 0 ] ) ) ; } catch ( Exception e ) { <START_BUG> throw new AssertionError ( ( "unable<seq2seq4repair_space>to<seq2seq4repair_space>parse<seq2seq4repair_space>args:<seq2seq4repair_space>" + args ) , e ) ; <END_BUG> } upgrader . upgrade ( ) ; Directory upgradedDir = newFSDirectory ( dir ) ; try { checkAllSegmentsUpgraded ( upgradedDir ) ; } finally { upgradedDir . close ( ) ; } } } public void testUpgradeOldSingleSegmentIndexWithAdditions ( ) throws Exception { } public static final String moreTermsIndex = "moreterms.40.zip" ; public void testMoreTerms ( ) throws Exception { } }

Fix:
throw new RuntimeException ( ( "unable<seq2seq4repair_space>to<seq2seq4repair_space>parse<seq2seq4repair_space>args:<seq2seq4repair_space>" + args ) , e ) ;